Clinicians may prescribe split pills for many different reasons, including dosing flexibility and patient affordability; however, this practice presents potential hazards. Splitting medications that are formulated to be extended-release or enteric-coated can lead to possibly dangerous changes in the drug's functionality. This study discusses the introduction of a clinical decision support warning that created a "hard stop" for any time an outpatient clinician attempted to prescribe a split pill for these special formulation medications. The study site was an academic medical center in Taiwan that performs more than 2.5 million ambulatory visits per year. The intervention resulted in a sharp decline in inappropriate medication splitting from a rate of approximately 0.61% to below 0.2%, where it has remained for at least 10 consecutive months. The use of a hard stop order can be controversial, as this method has resulted in unintended consequences in the past. A prior AHRQ WebM&M perspective discussed some of the tensions related to implementing medication decision support systems.